Hydraulic braking system for an automotive vehicle

Abstract

A hydraulic braking system for an automobile vehicle includes a first brake pressure control circuit and a second brake pressure control circuit, each of which includes a front solenoid valve disposed between one of the front wheel brakes and one of pressure chambers of a tandem master cylinder, a rear solenoid valve disposed between one of the rear wheel brakes and the pressure chamber, a hydraulic pump whose outlet communicates with a conduit located between the solenoid valves and the pressure chamber, a change over valve disposed between the solenoid valves and the pressure chamber, the change over valve being positionable in a first position which connects the solenoid valves to the pressure chamber and a second position which connects the inlet of the hydraulic pump to the pressure chamber, a front orifice disposed between the front wheel brake and the inlet of the hydraulic pump, a rear orifice disposed between the rear wheel brake and the inlet of the hydraulic pump, and a check valve disposed between the rear wheel brake and the inlet of the hydraulic pump for preventing brake fluid from flowing into the rear wheel brake.

What is claimed is: 
     
       1. A hydraulic braking system for an automobile vehicle having a pair of driven wheels and a pair of non-driven wheels, comprising: a tandem master cylinder having a first pressure chamber and a second pressure chamber;   a first primary conduit for connecting the first pressure chamber to a first wheel brake installed on one of the driven wheels and a second wheel brake installed on one of the non-driven wheels;   a first solenoid valve installed in the first primary conduit for being disposed between the first wheel brake and the first pressure chamber;   a second solenoid valve installed in the first primary conduit for being disposed between the second wheel brake and the first pressure chamber;   a first hydraulic pump having an outlet that communicates with a first junction portion of the first primary conduit located between the first and second solenoid valves and the first pressure chamber, and an inlet for communicating with the first wheel brake through a first relief conduit and for communicating with the second wheel brake through a second relief conduit;   a first change over valve disposed in the first primary conduit between the first junction portion and the first pressure chamber, the first change over valve being positionable in a first position in which the first and second solenoid valves are connected to the first pressure chamber and the inlet of the first hydraulic pump is disconnected from the first pressure chamber, and a second position in which the inlet of the first hydraulic pump is connected to the first pressure chamber and the first and second solenoid valves are connected to the first pressure chamber by way of the first hydraulic pump;   a first orifice disposed in the first relief conduit;   a second orifice disposed in the second relief conduit;   a first check valve disposed in the second relief conduit for preventing brake fluid from flowing into the second wheel brake;   a second primary conduit for connecting the second pressure chamber of the tandem master cylinder to a third wheel brake installed on the other driven wheel and a fourth wheel brake installed on the other non-driven wheel;   a third solenoid valve installed in the second primary conduit for being disposed between the third wheel brake and the second pressure chamber;   a fourth solenoid valve installed in the second primary conduit for being disposed between the fourth wheel brake and the second pressure chamber;   a second hydraulic pump having an outlet that communicates with a second junction portion of the second primary conduit located between the third and fourth solenoid valves and the second pressure chamber, and an inlet for communicating with the third wheel brake through a third relief conduit and with the fourth wheel brake through a fourth relief conduit;   a second change over valve installed in the second primary conduit between the second junction portion and the second pressure chamber, the second change over valve being positionable in a first position in which the third and fourth solenoid valves are connected to the second pressure chamber and the inlet of the second hydraulic pump is disconnected from the second pressure chamber, and a second position in which the inlet of the second hydraulic pump is connected to the second pressure chamber and the third and fourth solenoid valves are connected to the second pressure chamber by way of the second hydraulic pump;   a third orifice disposed in the third relief conduit;   a fourth orifice disposed in the fourth relief conduit; and   a second check valve disposed in the fourth relief conduit for preventing the brake fluid from flowing into the fourth wheel brake.   
     
     
       2. A hydraulic braking system for an automobile vehicle having a pair of driven wheels and a pair of non-driven wheels, comprising: a tandem master cylinder including a first pressure chamber and a second pressure chamber;   a first primary conduit for connecting the first pressure chamber to a first front wheel brake installed on one of front driven wheels and a first rear wheel brake installed on one of rear non-driven wheels;   a first from solenoid valve installed in the first primary conduit for being disposed between the first front wheel brake and the first pressure chamber;   a first rear solenoid valve installed in the first primary conduit for being disposed between the first rear wheel brake and the first pressure chamber;   a first hydraulic pump having an outlet that communicates with a first junction portion of the first primary conduit located between the first solenoid valves and the first pressure chamber, and an inlet for communicating with the first front wheel brake through a first front relief conduit and with the first rear wheel brake through a first rear relief conduit;   a first change over valve installed in the first primary conduit to be located between the first junction portion and the first pressure chamber, the first change over valve being adapted to be positioned in a first position in which the first solenoid valve is connected to the first pressure chamber and the inlet of the first hydraulic pump is disconnected from the first pressure chamber, and a second position in which the inlet of the first hydraulic pump is connected to the first pressure chamber and the first solenoid valve is connected to the first pressure chamber by way of the first hydraulic pump;   a first front orifice disposed in the first front relief conduit;   a first rear orifice disposed in the first rear relief conduit;   a first rear check valve disposed in the first rear relief conduit for preventing brake fluid from flowing into the first rear wheel brake;   a second primary conduit for connecting a second front wheel brake installed on the other from driven wheel and a second rear wheel brake installed on the other rear non-driven wheel to the second pressure chamber of the tandem master cylinder;   a second front solenoid valve installed in the second primary conduit for being disposed between the second front wheel brake and the second pressure chamber;   a second rear solenoid valve installed in the second primary conduit for being disposed between the second rear wheel brake and the second pressure chamber;   a second hydraulic pump having an outlet that communicates with a second junction portion of the second primary conduit located between the second solenoid valve and the second pressure chamber, and an inlet for communicating with the second front wheel brake through a second front relief conduit and with the second rear wheel brake through a second rear relief conduit;   a second change over valve installed in the second primary conduit between the second junction portion and the second pressure chamber, the second change over valve being positionable in a first position to connect the second solenoid valve to the second pressure chamber and disconnect the inlet of the second hydraulic pump from the second pressure chamber, and a second position to connect the inlet of the second hydraulic pump to the second pressure chamber and connect the second solenoid valve to the second pressure chamber by way of the second hydraulic pump;   a second from orifice disposed in the second from relief conduit;   a second rear orifice disposed in the second rear relief conduit; and   a second rear check valve disposed in the second rear relief conduit for preventing the brake fluid from flowing into the second rear wheel brake.   
     
     
       3. A hydraulic braking system for an automobile vehicle as recited in claim 2, further comprising a first front check valve disposed in the first front relief conduit for preventing brake fluid from flowing into the first front wheel brake, and a second front check valve disposed in the second front relief conduit for preventing brake fluid from flowing into the second front wheel brake. 
     
     
       4. A hydraulic braking system for an automobile vehicle having a pair of driven wheels and a pair of non-driven wheels, comprising: a tandem master cylinder having a first pressure chamber and a second pressure chamber;   a first primary conduit for connecting the first pressure chamber to a first wheel brake installed on a first one of the driven wheels and a second wheel brake installed on a first one of the non-driven wheels;   a first solenoid valve installed in the first primary conduit between the first wheel brake and the first pressure chamber for being moved between a first position in which brake fluid is supplied from the first pressure chamber to the first wheel brake and a second position in which brake fluid is prevented from being supplied to the first wheel brake from the first pressure chamber;   a second solenoid valve installed in the first primary conduit between the second wheel brake and the first pressure chamber for being moved between a first position in which brake fluid is supplied from the first pressure chamber to the second wheel brake and a second position in which brake fluid is prevented from being supplied to the second wheel brake from the first pressure chamber;   a first hydraulic pump having an outlet that communicates with a first junction portion of the first primary conduit located between the first and second solenoid valves and the first pressure chamber, and an inlet for communicating with the first wheel brake through a first relief conduit and for communicating with the second wheel brake through a second relief conduit;   a first change over valve disposed in the first primary conduit between the first junction portion and the first pressure chamber, the first change over valve being positionable in a first position in which the first and second solenoid valves are connected to the first pressure chamber and the inlet of the first hydraulic pump is disconnected from the first pressure chamber, and a second position in which the inlet of the first hydraulic pump is connected to the first pressure chamber and the first and second solenoid valves are connected to the first pressure chamber by way of the first hydraulic pump;   a first wheel speed sensor for being mounted on the first one of the driven wheels;   a first orifice disposed in the first relief conduit;   a second orifice disposed in the second relief conduit;   a first check valve disposed in the second relief conduit for preventing brake fluid from flowing into the second wheel brake;   a controller connected to the first wheel speed sensor, the first and second solenoid valves, the first hydraulic pump and the first change over valve so that upon detection of a slip condition in the first one of the driven wheels the controller positions the second solenoid valve in the second position, positions the change over valve in the second position, operates the first hydraulic pump and repeatedly moves the first solenoid valve between the first and second positions.   
     
     
       5. A hydraulic braking system for an automobile vehicle as recited in claim 4, further comprising a second primary conduit for connecting the second pressure chamber of the tandem master cylinder to a third wheel brake installed in the other driven wheel and a fourth wheel brake installed on the other non-driven wheel, a third solenoid valve installed in the second primary conduit between the third wheel brake and the second pressure chamber, and a fourth solenoid valve installed in the second primary conduit between the fourth wheel brake and the second pressure chamber. 
     
     
       6. A hydraulic braking system for an automobile vehicle as recited in claim 5, further comprising a second hydraulic pump having an outlet that communicates with a second junction portion of the second primary conduit located between the third and fourth solenoid valves and the second pressure chamber, and an inlet for communicating with the third wheel brake through a third relief conduit and with the fourth wheel brake through a fourth relief conduit. 
     
     
       7. A hydraulic braking system for an automobile vehicle as recited in claim 6, further comprising a second change over valve installed in the second primary conduit between the second junction portion and the second pressure chamber, the second change over valve being positionable in a first position in which the third and fourth solenoid valves are connected to the second pressure chamber and the inlet of the second hydraulic pump is disconnected from the second pressure chamber, and a second position in which the inlet of the second hydraulic pump is connected to the second pressure chamber and the third and fourth solenoid valves are connected to the second pressure chamber by way of the second hydraulic pump. 
     
     
       8. A hydraulic braking system for an automobile vehicle as recited in claim 7, further comprising a third orifice disposed in the third relief conduit, a fourth orifice disposed in the fourth relief conduit, and a second check valve disposed in the fourth relief conduit for preventing the brake fluid from flowing into the fourth wheel brake.